Field of the Invention
The present invention relates to a developing apparatus that develops an electrostatic latent image formed on a photosensitive drum, a process cartridge that forms a developer image on the photosensitive drum and is detachably attached to an apparatus main body of an image forming apparatus, and the image forming apparatus that forms an image on a recording medium by using a developer.
Description of the Related Art
Conventionally, in an image forming apparatus that uses electrophotographic techniques, a photosensitive drum charged by a charging roller is exposed by an exposure apparatus, and an electrostatic latent image is thereby formed on the photosensitive drum. The electrostatic latent image formed on the photosensitive drum is developed as a toner image by a developing apparatus, and the toner image on the photosensitive drum is transferred to a sheet such as a paper sheet. Subsequently, the toner image transferred to the sheet is fixed to the sheet by being heated and pressurized by a fixing apparatus.
Herein, in recent years, the charging roller, the photosensitive drum, the developing apparatus and the like are integrated as a process cartridge in the image forming apparatus. In addition, the process cartridge is detachably attached to the apparatus main body of the image forming apparatus. With this, by replacing the process cartridge, it is possible to perform, for example, replacement of process means such as the photosensitive drum and addition of toner. According to the process cartridge system described above, a user can perform the maintenance of the image forming apparatus, and hence it is possible to easily perform the maintenance of the image forming apparatus.
Herein, the frame of the developing apparatus in the process cartridge is conventionally formed by coupling a first frame and a second frame. In addition, by coupling the first frame and the second frame, a toner storage portion in which toner is stored, a developing chamber in which a developing roller is disposed, and an opening for conveying the toner from the toner storage portion to the developing chamber are formed in the developing apparatus. Further, conventionally, a seal member is provided in a gap between the developing roller and the frame in the vicinity of each of both end portions in the direction of the rotation center axis of the developing roller such that the toner does not leak from the gap between the developing roller and the frame.
In addition, conventionally, due to the displacement of the position of the seal member relative to the frame that is caused when the developing apparatus is assembled and the tolerance of the seal member, a gap has been formed between the seal member and the frame. To cope with this, in a technique disclosed in Japanese Patent Application Laid-open No. 2007-025345, in order to seal the gap between the seal member and the frame, elastomer is injected into the gap between the seal member and the frame. Specifically, an injection inlet for injecting liquid elastomer is provided in the frame, and the elastomer is poured into the gap between the seal member and the frame by injecting the elastomer into the injection inlet.
In the case of this configuration, it is proposed to adopt a configuration in which a fence for storing the elastomer spilling out of the injection inlet is provided (Japanese Patent Application Laid-open No. 2007-025345). The elastomer having spilled out of the injection inlet is stored in the fence provided around the injection inlet. With this, the injected elastomer is prevented from jutting out from the contour of the frame.
In recent years, the size of the image forming apparatus has been reduced. In order to reduce the size of the image forming apparatus, it is conceivable to adopt a configuration in which the fence for storing the elastomer is exposed to the path of the sheet conveyed in the image forming apparatus. However, when the elastomer or the fence for storing the elastomer is exposed to the path of the sheet, in the case where the sheet is curled, there is a possibility that the sheet comes into contact with the elastomer or the fence and jamming (paper jamming) is thereby caused.